This invention relates to systems and methods for delivering and deploying endovascular graft components within the vasculature of a patient.
It is well established that various fluid conducting body or corporeal lumens, such as veins and arteries, may deteriorate or suffer trauma so that repair is necessary. For example, various types of aneurysms or other deteriorative diseases may effect the ability of the lumen to conduct fluids and, in turn, may be life threatening. In some cases, the damage to the lumen is repairable only with the use of prosthesis such as an artificial vessel or graft.
An abdominal aortic aneurysm is a sac caused by an abnormal dilation of the wall of the aorta as it passes through the abdomen. The aorta is the main artery of the body, supplying blood to various organs and parts of the body. It arises from the left ventricle of the heart, passes upward, bends over and passes down through the thorax and through the abdomen, and finally divides into the two iliac arteries which supply blood to the pelvis and lower extremities. The aneurysm ordinarily occurs in the portion of the aorta below the kidneys. When left untreated, the aneurysm will eventually cause the sac to rupture with ensuing fatal hemorrhaging in a very short time. The repair of abdominal aortic aneurysms has typically required major abdominal surgery in which the diseased and aneurysmal segment of the aorta is removed and replaced with a prosthetic device, such as a synthetic graft.
For repair of vital lumens such as the aorta, surgical repair is significantly life threatening or subject to significant morbidity. Surgical techniques known in the art involve major surgery in which a graft resembling the natural vessel is spliced into the diseased or obstructed section of the natural vessel. Known procedures include surgically removing the damaged or diseased portion of the vessel and inserting an artificial or donor graft portion inserted and stitched to the ends of the vessel which were created by the removal of the diseased portion. More recently, devices have been developed for treating diseased vasculature through intraluminal repair. Rather than removing the diseased portion of the vasculature, the art has taught bypassing the diseased portion with a prosthesis and implanting the prosthesis within the vasculature. An intra arterial prosthesis of this type has two components: a flexible conduit, the graft, and the expandable framework, the stent (or stents). Such a prosthesis is called an endovascular graft.
As with all major surgeries, there are many disadvantages to the foregoing surgical technique, the foremost of which is the high mortality and morbidity rate associated with surgical intervention of this magnitude. Other disadvantages of conventional surgical repair include the extensive recovery period associated with such surgery; difficulties in suturing the graft to the aorta; the loss of the existing thrombosis to support and reinforce the graft; the unsuitability of the surgery for many patients, particularly older patients exhibiting co-morbid conditions; and the problems associated with performing the surgical procedure on an emergency basis after the aneurysm has already ruptured.
In view of the foregoing disadvantages of conventional surgical repair techniques, techniques have been developed for repairing abdominal aortic aneurysms by intraluminally delivering an aortic graft to the aneurysm site through the use of a catheter based delivery system, and securing the graft within the aorta using an expandable stent. Since the first documented clinical application of this technique, the technique has gained more widespread recognition and is being used more commonly. As vascular surgeons have become more experienced with this endovascular technique, however, certain problems have been encountered.
One of the drawbacks is that rigidity is preferred when maneuvering the delivery system through some portions of vasculature to a repair site while flexibility is preferred when maneuvering the delivery system through other portions of vasculature to a repair site. Furthermore, once the delivery system is at the repair site and the repair device has been deployed, flexibility is preferred when removing the delivery system from the vasculature.
Rigidity facilitates advancing the delivery system through some portions of vasculature by increasing pushability and torquability. Pushability and torquability allow the delivery system to be advanced through areas of the vasculature that are narrowed with a reduced risk that the delivery system may kink or bend. Flexibility facilitates advancing the delivery system through other portion of vasculature, such as tortuous or curved portions, by allowing the delivery system to conform to the vasculature, thereby reducing the risk of damage to the vasculature by the delivery system.
Once the delivery system is at the repair site and the repair device deployed, flexibility facilitates removing the delivery system from within the deployed repair device and retracting the delivery system from the vasculature. Flexibility allows the delivery system to be withdrawn from within the repair device with a reduced risk that the delivery system may get snagged on the repair device and allows the delivery system to conform to the anatomy, thereby reducing the risk of damage to the vasculature as the delivery system is withdrawn.
Another drawback is that precise deployment of a repair device at a repair site may require that the repair device not be deployed at an angle with respect to the vasculature in which it is embedded. A typical repair device for AAA has an anchor frame attached to a graft component, with the anchor frame deployed such that it is embedded in the vasculature at the neck of the aorta. Proper fixation and seal between the repair device and the aorta neck depends upon the anchor frame of the repair device being substantially parallel to the neck when it is deployed. If the anchor frame is deployed at an angle with respect to the neck, a proper seal may not be obtained and leakage may occur.
A rigid delivery system, which may be advantageous for advancement through the vasculature, will not follow the contour of the neck anatomy, thereby making proper deployment of the anchor frame difficult. A flexible delivery system, on the other hand, will conform to the neck anatomy, thereby facilitating deployment of the anchor frame substantially parallel to the neck and a proper seal.
With regard to the method of delivery and deployment of endovascular graft components, there therefore exists a need for a endovascular graft delivery system that allows the flexibility of the delivery system to be varied. Furthermore, there exists a need for a delivery system that facilitates control of the portion of the delivery system containing the repair device such that the anchor frame may be deployed substantially parallel to the wall of the vasculature. The present invention addresses these and other needs.